This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In this proposed study (A5212), palifermin will be tested in HIV-1 infected patients to see whether palifermin can help to increase the CD4+ lymphocyte count in patients who have HIV-1 suppressed with active HIV medications but a poor recovery of CD4+ lymphocytes. Patients with a completely suppressed HIV-1 in blood but a low CD4+ lymphocyte count will be able to enroll in this study. Three different doses of palifermin will be compared with placebo (no active medication). Participants will receive either palifermin 20mcg/kg per day, 40mcg/kg per day, 60mcg/kg per day or placebo (salt water, no active medication). HIV-1 infected patients who want to participate in this study will receive an intravenous injection of palifermin or placebo on three consecutive days. Twelve weeks after the treatment with palifermin or placebo, the CD4+ lymphocyte count will be measured and the response in the different treatment groups will be compared. Additionally, the thymic function will be assessed by measuring the size via a computer tomography and by assessing the function by measuring a thymus stimulation product in blood (called T cell receptor excision circle or TREC in short). Also, general laboratory labs will be drawn to evaluate for any possible side effects and to determine the safety of palifermin.